1. Field of the Invention
This invention relates to a film end holding device in which a photosensitive material such as sheet film taken up on a recording drum of a drum type image scanning and recording apparatus and drawn by vacuum suction is prevented from being released from a surface of the drum during rotation thereof.
2. Prior Art
In the recording section of a conventional drum type image scanning and recording apparatus, it is known that a photosensitive material such as sheet film or photographic printing paper (hereinafter referred to as "film") is detained at its initial end portion by engaging at least two slits formed near the film end at a certain distance with pins disposed on the periphery of each drum in parallel to the axis at the same distance and number as said slits, and/or fixed by taping. The film is then taken up on a recording drum being squeezed by a squeezing roller or under a certain tension, and the film end is either detained by terminal end pins or fixed to the drum by taping, etc. Further, the film is extensively fastened to the periphery of the recording drum being drawn by vacuum suction by way numerous small apertures formed on the periphery.
With such film holding methods, since the films are treated in a dark room, taping of the film end to the drum surface is difficult. Moreover, it is necessary for the terminal end of the film to be pasted up to prevent distortion in the recording image (linear distortion, desirable accuracy is less than 10 .mu.m) while keeping the appropriate tension to the film. However, but such a paste up operation requires a certain level of skill and becomes more difficult with a larger film size. This means that the results of the pasting up operation vary depending on the skill of individual workers. A further problem exists in that surfaces of the drum and the film are stained by adhesive materials. Furthermore, when the initial end of a film is detained by two pins, for example, sagging may occur in the middle portion of the film due to the weight of the film itself, eventually causing the linear distortion in the recording image.
It is also to be noted that a rather complicated and expensive device is required for automatization of film setting and removing, i.e., a series of operations such as detention of the film terminal end by pinning or taping to keep a certain tension, and detaching the film from the drum after exposure.
When a film is fixed to the drum surface using vacuum suction alone without pinning and taping, a still further problem arises in the case of power failure or malfunction of a vacuum suction device, i.e., the film unavoidably and unexpectedly releases from the drum surface, resulting in a loss thereof.